The Islamic Republic’s ability to surveil the Strait of Hormuz and lay mines in the vital waterway has likely been significantly degraded by US attacks, the Institute for the Study of War assessed, noting that increased oil flows through the strait on September 1 suggest Iran is having difficulty preventing some commercial vessels from using the southern route.
US officials told Axios on Wednesday that approximately 40 vessels carrying millions of barrels of oil transited the Strait of Hormuz on September 1. US Energy Secretary Chris Wright also confirmed that oil tankers transported more than 17 million barrels of oil through the strait on August 31, the highest volume of oil exports through the waterway since the start of the US-Israel-Iran war.
The 17 million barrels is close to pre-war levels, which averaged 21.6 million barrels per day in the fourth quarter of 2025.
These developments, according to ISW, suggest that Iran is having difficulty preventing some commercial vessels from using the southern route.
Additionally, ISW reported growing indications that Iranian forces are facing operational constraints that are preventing them from efficiently identifying vessels and laying mines in the strait.
IRGC turns to alternative methods as Hormuz surveillance is degraded
According to ISW, the IRGC recently attempted to use shore-based rocket launchers instead of fast-attack craft to deploy mines. It has also reportedly used fast-attack craft to physically identify vessels because Iran has only a few functioning radars capable of covering the southern route. ISW assessed that these less-optimal methods suggest that US strikes have degraded some of Iran’s maritime surveillance and mine-laying capabilities.
Though the IRGC has repeatedly claimed that vessels are striking naval mines in the strait, ISW assessed that the claims likely form part of an effort to preserve the perception that the southern route remains dangerous. US Central Command previously reported that US forces had cleared naval mines from the strait.
CENTCOM commander Adm. Brad Cooper said last week that US forces had cleared an effective pathway for ships to leave the Persian Gulf, adding that the mines had been “highly degraded.”
However, Ebrahim Zolfaghari, an Iranian military officer and spokesperson, claimed on Wednesday that new mines had been laid.
“During last night's operation, more naval mines were laid along the illicit routes south of the Strait of Hormuz; The only thing CENTCOM could do in response was rename the Strait using Photoshop,” he wrote on X. “Problem solved! You can just use Photoshop to get the oil tankers through, too!”
Iran appears to be investing in rebuilding its radar systems, ISW noted, citing a claim by US President Donald Trump that Iran had nearly rebuilt some of its radar systems before the US struck them again on September 1.
CENTCOM September 1st strikes Iranian targets
CENTCOM confirmed that its strikes on September 1 targeted Iranian air defense sites, radar systems, maritime assets and facilities, mine-laying capabilities and communications sites. ISW assessed that Iran is likely to continue attempting to reconstitute these capabilities because control of the Strait of Hormuz remains one of Tehran’s core objectives.
With its radars degraded, ISW suggested Iran would seek alternative ways to attempt control over the strait. An unnamed American source told Saudi-based Al Arabiya on Wednesday that CENTCOM’s Tuesday night strikes were a preemptive response to Iran considering disabling undersea cables.